Shaking, wheezing chicken.

Please help. My 6 month old silver laced Wyandotte isn't feeling well. She has been having loose bowels that are greenish in color and keep getting caught in her feathers. She also has been shaking a bit for a number of days. Yesterday I thought she was taking her last breath - her mouth was totally open and she was gasping for air. Today she still has a bit of a rattle in her lungs. Her tail is usually down. I have brought her inside now and am hoping for some advice on what to feed her to help bring her back to good health. Any suggestions on how to treat her ailments and what might be causing them?

I've had several chickens die from something just like that. We currently have one little girl sick right now and she opens her mouth and gasps for air every breath. We've been giving her cooked millet w/ nutritional yeast and ground tumeric w/ water. Seems to help a little but she isn't noticeably better. It's odd that Joone, unlike all the other chickens we've had with this mysterious disease, has curled up legs.